Field of the Invention
The present invention relates to the blending of fuels with one or more alcohols. More particularly, the present invention relates to systems and processes for blending ethanol and/or butanol with gasoline which can be at a refinery.
Background Art
Global demand for liquid transportation fuel is projected to strain the ability to meet certain environmentally driven goals, for example, the conservation of oil reserves. Such demand has driven the development of technology which allows utilization of renewable resources to mitigate the depletion of oil reserves. This invention addresses the need for improved alternative fuel compositions and processes which allow for the conservation of oil reserves. Such compositions and processes would satisfy both fuel demands and environmental concerns.
Alcohols such as butanol and ethanol are blended with both finished gasoline and gasoline subgrades (e.g., blendstocks for oxygenate blending). The use of butanol in fuel blends has several advantages over ethanol. For example, because butanol has an energy content closer to that of gasoline, consumers face less of a compromise on fuel economy. Butanol has a low vapor pressure, meaning that it can be easily added to conventional gasoline. Also, butanol's chemical properties allow it to be blended with gasoline and gasoline subgrades at higher concentrations than ethanol. For example, butanol can be blended by at least 16% by volume in gasoline, thereby displacing more gasoline per gallon of fuel consumed than the standard 10% by volume ethanol blend.
Fuel blended directly at an oil refinery can be shipped by pipeline or marine vessel as finished gasoline. It is not desirable to blend alcohols such as ethanol with gasoline or gasoline subgrades directly at an oil refinery because ethanol mixes with the water typically present when shipping by pipeline or marine vessel. Butanol fuel blends are less susceptible to separation in the presence of water than ethanol fuel blends. The transportation of alcohol and fuels to loading terminals for blending incurs additional transportation costs which could be avoided if the alcohol could be blended with the gasoline or gasoline subgrade directly at the refinery.
What are needed are systems and processes for the production of fuels and fuel blends which are economical, and systems and processes in which the fuel blends can be produced. The present invention satisfies these and other needs, and provides further related advantages, as will be made apparent by the description of the embodiments that follow.